The present invention relates to a dispensing system for providing an alternative means for feeding items, such as elements, sheets of paper or the like, from an item source to a dispensing path when a primary means fails to feed an item from the item source to the dispensing path, and particularly to a dispensing system for automatically providing an alternative vacuum path to a sheet of paper, such as a document, a bill or currency, that is to be vacuum picked from a sheet source when a primary vacuum path fails to pick up the sheet because of a flaw in the sheet at a location at which the primary vacuum path contacts the sheet.
The normal system for picking sheets from a stack uses an oscillating tube with two arms attached. These arms contain suction cups connected through the tube to a vacuum pump. The tube is turned carrying the suction cups into contact with the front sheet of paper. This contact is made in the lower portion of the sheet near its outer edges. At the time of contact, a vacuum is applied to the suction cups, causing them to adhere to the front sheet of paper. The direction of rotation of the tube is then reversed, carrying the lower portion of the top sheet through an arc which places the edge of the sheet in the open portion of an interrupted circumference drive roller (a "D" shaped roller) of a transport mechanism. When the full circumference portion of the drive roller contacts its associated tension or pinch roller, the sheet of paper is then pulled off the stack and placed in the transport mechanism.
As a practical matter, a system for picking sheets from a stack is designed to handle not only a new paper, but also used paper sheets, such as currency, bills and documents, which have been handled and carried by the public. Used paper sheets sometimes contain flaws, such as corner folds and other deep creases and folds, as well as tears and holes. Occasionally, the presence of one or more of these flaws in a sheet will make it impossible for the vacuum cups to seal sufficiently against that sheet to establish a level of vacuum necessary to cause that sheet to separate from the stack. When this event occurs, the equipment ordinarily must be taken out of service.
The present invention relates to a sheet dispensing system and is specifically adapted to minimize the down time of the system due to flaws in used sheets of paper in the stack. Since such a failure of the system is caused by a flaw in the paper sheet at the primary locations at which the primary suction cups make contact with the sheet, secondary locations are chosen for two auxiliary suction cups to make contact with the sheet. These secondary locations are far enough away from the primary locations that a flaw causing a failure in the primary locations will not normally affect a vacuum in the secondary locations.
The background art known to applicant at the time of the filing of this application is as follows:
U.S. Pat. No. 3,617,048, Vacuum Paper Feeder, by D. J. Albert;
U.S. Pat. No. 3,954,260, Paper Money Dispensing Mechanism, by H. Morello et al;
U.S. Pat. No. 3,999,795, Vacuum Pad System, by L. B. Barker; and
U.S. Pat. No. 4,146,217, Sheet Feed Mechanism For Offset Printing Machines And The Like, by R. J. Barker.